Chemie und Prozesstechnik
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- 1 Analytische Chemie; Referenzmaterialien (100) (entfernen)
Eingeladener Vortrag
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Die Vorgehensweise bei der Zertifizierung von Referenzmaterialien in der BAM entsprechend den Regeln des ISO-Guide 35 wird an Beispielen beschrieben. Darüber hinaus wird ein umfassender Überblick über Referenzmaterialien zur Analyse der Nichtmetalle Sauerstoff, Wasserstoff, Stickstoff, Kohle und Schwefel gegeben.
Um in einem veränderten Umfeld erfolgreich bestehen zu können, müssen Chemieunternehmen neue Pfade beschreiten. Dazu gehört insbesondere das Potential digitaler Technologien. Mit flexiblen, modularen chemischen Vielzweck-Produktionsanlagen lassen sich häufig wechselnde Produkte mit kürzeren Vorlauf- und Stillstandzeiten zwischen den Kampagnen und dennoch hoher Qualität realisieren. Intensivierte, kontinuierliche Produktionsanlagen erlauben auch den Umgang mit schwierig zu handhabenden Substanzen.
Grundvoraussetzung für solche Konzepte ist eine hochautomatisierte "chemische" Prozesskontrolle zusammen mit Echtzeit-Qualitätskotrolle, die "chemische" Informationen über den Prozess bereitstellt. In einem Anwendungsbeispiel wurde eine pharmazeutische Lithiierungsreaktion aus einer modularen Pilot-Anlage betrachtet und dabei die Vorzüge eines vollautomatischen NMR-Sensors untersucht. Dazu wurde ein kommerziell erhältliches Benchtop-NMR-Spektrometer mit Permanentmagnet auf die industriellen Anforderungen, wie Explosionsschutz, Feldkommunikation und vollautomatischer, robuster Datenauswertung angepasst. Der NMR-Sensor konnte schließlich erfolgreich im vollautomatischen Betrieb nach fortschrittlichen Regelkonzepten und für die Echtzeitoptimierung der Anlage getestet werden. Die NMR-Spektroskopie erwies sich als hervorragende Online-Methode und konnte zusammen mit einer modularen Datenauswertung sehr flexibel genutzt werden. Die Methode konnte überdies als zuverlässige Referenzmethode zur Kalibrierung konventioneller Online-Analytik eingesetzt werden.
Zukünftig werden voll integrierte und intelligent vernetzte "smarte" Sensoren und Prozesse eine kontinuierliche Produktion von Chemikalien und Pharmazeutika mit vertretbaren Qualitätskosten möglich machen.
Asymmetrical laser-induced plasmas were investigated by a tomography approach based on the inverse Radon transform. Two distinct sources of asymmetricity were investigated: double-pulsed laser-induced plasmas in the orthogonal configuration and single-pulsed laser-induced plasmas under an inclined incidence angle. Both cases were observed at various delay times. The optical thinness of the laser-induced plasmas was achieved by appropriately adjusting the pulse energies. High temporal resolution is achieved by a gated intensified charge-coupled-device camera. The asymmetrical laser-induced plasmas are investigated in terms of their total emissivity, spectrally resolved emissivity, and temperature. The latter is obtained by the Saha–Boltzmann plot method. The images required for the inverse Radon transform technique were obtained with a high angular accuracy and reproducibility provided by mounting the spectrometer on a high-precision nano-positioning rotary stage. The plasmas were induced in the center of rotation of the stage. This arrangement allows the reconstruction of emissivity, which is integrated over a full spectral range (200-800 nm) or over a desired spectral range selected by a bandpass filter (~10 nm). It also allows for the reconstruction of spectrally-resolved emissivity in each cross sectional plasma slice by scanning the plasma across a spectrometer slit. The 3D maps of temperature and electron density are thus obtained for different types of asymmetric plasmas.
The Dark Side of Science
(2019)
The Joint Summer School of the two Marie Skłodowska-Curie Innovative Training Networks (ITN) “BioCapture” and “GlycoImaging”, funded by the EU within the Horizon 2020 framework programme, which are both devoted to the development of new methods for cancer biomarker and cancer cell detection, will take place at the Adlershof Campus of BAM. 19 Early stage researchers of both projects will convene, discuss their own science and plan future collaborative research. Training in scientific writing (instructor: Luita Spangler, Free University of Berlin), an employability workshop (Antti Kapanen, University of Applied Sciences Berlin) and first contacts with the “dark side of science” (Brian R. Pauw, BAM) will complement the programme of the summer school.
Magnesium (Mg) is a major element in a range of silicate and carbonate minerals, the hydrosphere and biosphere and plays important roles in (bio-) geochemical and physiological cycles. Mg has three stable isotopes, 24Mg, 25Mg and 26Mg with natural abundances of 79 %, 10 %, and 11 %, respectively. It is due to their relatively large mass difference (~8% between 24Mg and 26Mg) that isotope fractionation leads to slight variations of isotope amount ratios n(26Mg)/n(24Mg) in biological, environmental and geological samples. Traditionally, isotope ratios are measured by mass spectrometric methods and isotope ratios are expressed as deviation from an internationally agreed upon material, i.e. the zero-point of the δ-value scale. Drawbacks of this method include the high costs for instruments and their operation, experienced operators and elaborate, time-consuming chromatographic sample preparation.
Recently, optical spectrometric methods have been proposed as faster and low-cost alternative for the analysis of isotope ratios of selected elements by means of high- resolution continuum source graphite furnace molecular absorption spectrometry (HR- CS-GFMAS) and laser ablation molecular isotopic spectrometry (LAMIS).
For the determination of Mg isotope amount ratios, the molecular spectrum of the in-situ generated MgF and MgO molecules were studied. In the case of HR-CS-GFMAS, the absorption spectrum was recorded for MgF for the electronic transitions X2Σ → A2Πi and X 2Σ → B2Σ+ around wavelengths 358 nm and 268 nm, respectively. In the case of LAMIS, we investigated the MgF molecule for the electronic transition A2Πi → X2Σ as well as the MgO molecule for the electronic transition A1Π+ → X1Σ around 500 nm. The MgF and MgO spectra are described by the linear combination of their isotopic components or isotopologues: 24MgF, 25MgF, and 26MgF for the MgF and 24MgO, 25MgO, and 26MgO for the MgO (F is monoisotopic, and the isotope composition of O is assumed as constant). By HR-CS-GFMAS the analysis of Mg was done by deconvolution of the MgF spectrum by partial least square regression (PLS) calibrated with enriched isotope spikes. Isotope amount ratios in rock samples with and without matrix separation were analyzed. Calculated δ-values were accurate and obtained with precisions ranging between 0.2 ‰ and 0.5 ‰ (1 SD, n = 10). On the other hand, LAMIS allows the direct analysis of solid samples with the extended possibility of in-situ analysis. Main advantages, limitations, and scopes of both optical techniques are going to be discussed and compared to MC-ICP-MS.
Magnesium is a naturally occurring element that can be found in several mineral forms in the earth crust. This element presents three stable isotopes 24Mg, 25Mg and 26Mg with a natural abundance of 79%, 10%, and 11% respectively. It is due to their relatively large mass difference (~8% between 24Mg and 26Mg) that isotope fractionation leads to slight isotope amount ratio variations n(26Mg)/n(24Mg) in biological and geological samples. Traditionally, isotope amount ratios have been measured by mass spectrometric methods. However, drawbacks of these methods include the high costs for instruments and their operation, experienced operators and elaborate chromatographic sample preparation which are time-consuming. Recently, optical spectrometric methods have been proposed as faster and low-cost alternative for the analysis of isotope ratios of selected elements by means of high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) and laser ablation molecular isotopic spectrometry (LAMIS). For the determination of Mg isotope amount ratios, the molecular spectrum of the in-situ generated MgF and MgO molecules were studied. In the case of HR-CS-GFMAS, the absorption spectrum was recorded for MgF for the electronic transitions X 2Σ → A 2 Πi and X 2Σ → B 2Σ+ around wavelengths 358 nm and 268 nm respectively. In the case of LAMIS, it was studied the MgF molecule for the electronic transitions A 2Πi → X 2Σ as well as the MgO molecule for the electronic transition A 1Π+ → X 1Σ around 500 nm. The MgF and MgO spectra are composed by the linear combination of their isotopic components or isotopologues: 24MgF, 25MgF, and 26MgF for the MgF and 24MgO, 25MgO, and 26MgO for the MgO (F is monoisotopic, and the isotope composition of O is assumed as constant). By HR-CS-GFMAS the analysis of Mg was done by deconvolution of the MgF spectrum by a partial least square regression (PLS) calibrated with enriched isotope spikes. The isotope amount ratios in rock samples with and without matrix separation were analyzed. Resulting delta values were obtained with precisions ranging between 0.2-0.5 ‰. On the other hand, LAMIS allows the direct analysis of solid samples with the extended possibility of in-situ analysis. Main advantages, limitations, and scopes of both optical techniques are going to be discussed and compared with MC-ICP-MS.
Simultaneous multielemental analysis of crude oils by high-resolutions absorption spectrometry
(2019)
When crude oil arrives at a refinery it needs a lot of processing before it is suitable for cracking into lighter fractions. Sulfur has to be extracted to meet ultra-low sulfur legislation for most of the fuel grades, and desalination is a crucial process as chlorine within salts is corrosive to refinery equipment. Measuring the amounts of sulfur and chlorine within crude oil is the first step in a complex clean-up process.
Heavy metals, such as vanadium, nickel and iron need to be removed too. These metals can poison the catalyst used to crack the oil into lighter fractions. This is costly as it reduces the useful life of the catalyst. Like chlorine, heavy metals also have a corrosive effect on the plant. There is some evidence that the presence of some metals in the final product can reduce performance.
A fast determination of elements and size of suspended particles is vital for diagnosis and safeguard of refinery equipment. However, sample preparation for current analytical methods consumes precious time and lost particle size information.
High-resolution continuum source graphite furnace absorption spectrometry (HR-CS-GFAS) is proposed as a fast analytical method for elemental determination in crude oils and potentially for simultaneous multielement and particle size analysis. This HR-CS-GFAS instrumentation is coupled to a modular simultaneous echelle spectrometer (MOSES) and provides a full optical window with high resolution (from 180 to 900 nm with bandwidth λ/170,000). By using this set-up, it is possible to generate a multiparameter 3D spectral image (atomic and molecular lines, isotopic shift, atomization delay, and intensities). The generated spectral images can be analyzed by multivariate regressions for the elemental and particle size analysis. Additionally, if several atomic and molecular lines are simultaneously measured, they may be used in multi-energy calibration (MEC), a method based on the use of many wavelengths of the same absorbing/emitting entity to improve the accuracy in analytical atomic spectrometry. This MEC approach combined with multivariate image analysis allows the quantification of selected elements (Si, Al, Ni, Fe, V, S, and Cl) and overcomes matrix effects.
Shortly after founding the CCQM in 1993, the first key comparison (CCQM-K2) about the determination of Cd and Pb content in river water was hosted by IRMM. It has been clear from the beginning that for the determination of an element mass fraction in a matrix, accurate reference solutions would be the key point for a metrologically sound analysis. Triggered by the not entirely satisfactory results it was decided to investigate the basis of all measurements: the reference solutions. Thus in 1999, CCQM-K8, hosted by EMPA/LNE, started the tedious but indispensable work on elemental solutions standards.
Additionally, PTB, BAM and Merck KGaA initiated a project to establish a traceability system for inorganic analysis based on accurate monoelemental solutions. Within this unique approach ten high purity reference materials were fully characterized, and solutions were prepared gravimetrically thereof. These materials (forming the primary standards of elemental analysis) are available for NMIs/DIs from BAM.
CCQM-P46 (Cu, Mg, Rh) demonstrated the actuality of the topic and the challenges to prepare elemental solutions for every element. The accurate preparation and use of monoelemental solutions is consequently reflected in the recurrent conduct of (key) comparisons: CCQM-P149 (purity of zinc), CCQM-K87 (Co, Cr, Pb), and the current CCQM-K143/P181 (Cu solutions), to name only a few in a long series.
Is it necessary to put so much effort into the preparation of reference solutions? It clearly is! An example outside the world of academia: Recently, EDQM*, PTB, BAM and JRC have developed monoelemental reference standards traceable to the SI for toxic elements in support of the chapters of the European Pharmacopoeia, related to the analysis of elemental impurities in medicinal products. A new ICP OES method has been established allowing the comparison of two 1 g/kg mercury solutions with an outstandingly small uncertainty of Urel(w(Hg)) = 0.16 %. However, this technical progress would not have been possible without the ongoing effort of the metrological community within 25 years of research in the field of high accuracy monoelemental solutions.
* EDQM: European Directorate for the Quality of Medicines and HealthCare
Si isotope fractionation during BIF formation – inferences from a modern Archean ocean analogue
(2019)
Silica-rich sedimentary rocks like cherts and BIFS, typical for the Archean, have been used to reconstruct temperatures and other properties of the early oceans through the study of their Si isotope variations. Precambrian cherts and BIFS span a δ30Si range of ~7‰, with BIFs being about 2‰ lower in δ30Si than cherts. These lower δ30Si signatures have been attributed to represent contributions from different input sources such as hydrothermal fluids, variable continental weathering regimes or sorption onto Fe oxides/hydroxides [e.g. 2 and references therein]. In this study, fluids and BIF-like sediments have been investigated for their Si isotope compositions in Paulina Lake (PL), a hydrothermally-influenced crater lake in the Newberry Caldera, Oregon, USA. PL lake sediments are rich in silica (~65wt% SiO2) and are composed of up to 22.5wt% Fe2O3, which is comparable to Archean BIFs and thus serve as a modern Archean ocean analogue. We compared our analyses with East Lake (EL), the twin Newberry crater lake without hydrothermal input. Dissolved Si in EL has an average δ30Si signature of +1.55±0.16‰ (1sd) and sediments an average δ30Si signature of +0.18±0.28‰ (1sd). Dissolved Si in PL has an average δ30Si signature of +2.02±0.15‰ (1sd), whereas the sediments show a large range in δ30Si values between +0.59‰ and -1.24‰. PL sediments show a trend towards more negative δ30Si with increasing Fe2O3 contents. The magnitude of Si isotope fractionation thus appears to depend on the presence of Fe. This fractionation induced by interaction with Fe precipitation is defined here as the offset in δ30Si between PL and EL sediments at comparable depths (Δ30SiPL-EL). The resulting Δ30SiPL-EL values range between +0.69 and -1.42‰ and increase with increasing Fe2O3 content in the sediments. Our results are the first to quantify the magnitude of Fe-induced δ30Si fractionation observed in a natural analogue of the Archean ocean and can explain the lighter δ30Si signatures found in BIFs.